Influenza is a critical public health concern and each year 3,000-52,000 people die from influenza infection the United States. Influenza is a constantly evolving pathogen that has rapidly developed resistance to currently approved antivirals. Rapid diagnosis and typing of influenza infection plays a vital role in surveillance and use of antiviral therapeutics. Recently, several ELISA kits that use antibodies for influenza detection have been approved for use in point-of-care facilities but there have been concerns with the variability, sensitivity, selectivity and stability of these tests, illustrating the need for additional influenza affinity ligands. Ideally, these ligands could be used in diagnostic and therapeutic applications and should be rapidly produced to keep pace with viral antigenic drift and shift.
International Publication No. WO08/048970, published Apr. 24, 2008, and entitled “Synthetic Antibodies” describes methods for isolating a class of molecules termed synthetic antibodies or synbodies. Synbodies contain at least two compounds, such as short peptides, joined via a linker. Although the affinity of individual compounds for a target is typically weak, the combination of compounds can bind desired target with affinities comparable to antibodies. Synbodies have advantages over antibodies resulting in part from their smaller size. These advantages may include ease of initial isolation, ease and cost of production, and improved tissue penetration. Synbodies, can be developed by linking two low affinity 15-20 amino acid (aa) long peptides to produce a high affinity synbody for a target protein or bacteria.
In general, synbodies comprising affinity elements and linkers that can be synthesized by standard solid phase synthesis techniques can be synthesized either by addition of amino acids or other monomers in a stepwise fashion, or by joining preassembled affinity elements and linkers or other presynthesized subunits. Techniques for stepwise synthesis of peptides and other heteropolymers are described by e.g., Atherton E, Sheppard R C: Solid Phase peptide synthesis: a practical approach. Oxford, England: IRL Press; 1989, and Stewart J M, Young J D: Solid Phase Peptide Synthesis, 2d Ed. Rockford: Pierce Chemical Company; 1984, which are incorporated herein by reference. Examples of conjugation chemistries have been discussed in International Patent Application Publication Nos. WO08/048970 and WO/2009/140039, published Nov. 19, 2009. The use of “click” chemistry to perform conjugations between biopolymers and other heteropolymers is also described in Kolb et al., Angewandte Chemie-International Edition 2001, 40(11):2004 and Evans, Australian Journal of Chemistry 2007, 60(6):384-395, which are incorporated herein by reference.